This invention relates to process controllers and more particularly to an intelligent programmable process control system.
Process controllers have been utilized in recent years for controlling processing machines and manufacturing lines and the like. The systems operate on boolean logic which is programmed into the controller by means of a stored program supplied by the user. The program may be stored in a permanent or removable read-only memory (ROM) to control a particular process or machine in the same manner continuously (or until a new ROM is supplied) or, the program may be stored in a random access memory (RAM) which program may be changed at will. The industrial process controller, following the stored set of boolean equations receives inputs from sensors (photodiodes, pressure switches, etc.) located throughout the processing or manufacturing equipment as well as inputs from timers, etc., and in response thereto, generates signals for controlling the various operating devices of the processing or manufacturing equipment such as solenoids, motors, valves, etc. See, for example, U.S. Patents to Henry et al (U.S. Pat. No. 3,938,104) "System for Modifying a Logic Controller Instruction Set"; Naud (U.S. Pat. No. 3,924,242) "System for Building Op Codes"; Burkett et al (U.S. Pat. No. 3,953,834) "Programmable Logic Controller With Push Down Stack" Burkett et al (U.S. Pat. No. 4,030,080) "Variable Module Memory"; Burkett et al (U.S. Pat. No. 4,092,730) "Data Processor With Read Only Memory Processor and Partial Solution Push-Down Stack"; and, Burkett et al (U.S. Pat. No. 3,982,230) "Programmable Logic Controller With Flag Storage", each being assigned to the assignee of the present invention, as well as the prior art of record with respect to each of said patents. These process control systems are all hard-wired logic systems.
With the recent widespread commercialization of the microprocessor, the ability of replacing the hard-wired logic of industrial controllers with a microprocessor has greatly simplified the circuitry of the industrial controller as well as provided a degree of "intelligence", the ability of the controller not only to control process parameters, but also to mathematically compute parameters as well.
The present invention has gone many steps further in increasing the ability and efficiency of a microprocessor-based intelligent process controller.
It is therefore an object of the present invention to provide an improved intelligent programmable process control system.
Another object of the present invention is to provide a microprocessor-based process control system with intelligent parameter computation ability as well as boolean logic parameter control.
It is another object of the invention to provide an improved process controller with both analog and digital input/output capability.
It is still a further object of the invention to provide a process controller with a capability of making complex mathematical computations.
Yet another object of the present invention is to provide a process controller with multiple process control loops.
Still another object of the invention is to provide an improved process controller having each of the above features in one compact system.